A number of N-arylisoxazol-5(2H)-ones (aryl = phenyl, isoquinolin-1-yl, quinolin-2-yl, 2-phenylquinazolin-4-yl and benzothiazol-2-yl) have been reacted with lithium azide to give 2-(1-aryltetrazol-5-yl)acetic esters, which have been C- methylated and hydrolysed. The resulting 2-(1-aryltetrazol-5-yl) propanoic acids had low antiinflammatory activity, as judged by inhibition of synthesis of prostaglandin PGE2 or tumour necrosis factor α.
Ethyl 5-oxo-2,5-dihydroisoxazole-4-carboxylate has been treated with a number of chlorinated heterocycles to yield the corresponding substitution products: ethyl 2-(isoquinolin-1-yl)-5-oxo-2,5-dihydroisoxazole-4-carboxylate, ethyl 5-oxo-2-(quinolin-2-yl)-2,5- dihydroisoxazole-4-carboxylate, ethyl 5-oxo-2-(purin-2-yl)-2,5- dihydroisoxazole-4-carboxylate, ethyl 5-oxo-2-(pyrimidin-2-yl)-2,5-dihydroisoxazole-4-carboxylate, ethyl 2-(6-chlorpyridazin-3-yl)-5-oxo- 2,5-dihydroisoxazole-4-carboxylate, ethyl 2-(benzothiazol-2-yl)-5-oxo- 2,5-dihydroisoxazole-4-carboxylate, 2- and 6-(4-ethoxycarbonyl-5-oxo-2,5-dihydroisoxazol-2-yl)pyridine-3-carboxylic acid, ethyl 5-oxo- 2-(2-phenylquinazolin-4-yl)-2,5-dihydroisoxazole-4-carboxylate and ethyl 2-(2,4-diaminotriazin-2-yl)-5-oxo-2,5-dihydroisoxazole-4- carboxylate . The compounds generally cause loss of motor control in mice, but are relatively toxic.